NAD (P)H:quinone oxidoreductase1 (NQO1) and NRH:quinone oxidoreductase2 (NQO2) are enzymes that generally detoxify quinones, and protect against oxidative stress. NQO1-/-, NQO2-/-, and double knockout (DKO) mice were generated in our laboratory. All were born normal, however, NQO1-/- mice exhibited painful bladder syndrome (PBS). Microarray analysis of bladders from wild type and NQO1-/- mice revealed that PPA?C1?/MUP1/MUP2 factors regulating mitochondrial biogenesis, energy metabolism and adhesion were down regulated in NQO1-/- mice. However, the mechanism by which NQO1 controls these factors remains unknown. Epidemiological studies have shown an association between human NQO1P187S mutation and cigarette smoke related bladder cancer. This suggests a role of NQO1 and possibly NQO2 in cigarette smoke- induced bladder cancer that remains to be elucidated. DKO mice showed hyperoxic lung injury/infiltration with neutrophils. This together with epidemiological reports of association between NQO1P187S mutation and asthma raise intriguing questions regarding the role of NQO1/NQO2 in cigarette smoke-induced pulmonary emphysema. NQO1-/-, NQO2-/- and DKO mice demonstrated significantly higher susceptibility to develop skin tumors in response to benzo(a)pyrene and DMBA, as compared with wild type mice. Further studies revealed that NQO1 and NQO2 stabilization of tumor suppressor p53 against 20S proteasome degradation and down regulation of p63 and MAPK pathway contributed to carcinogenesis. However, a complete mechanism remains unknown and warrants further investigation. Studies have suggested that stress-inducible NQO1 and NQO2 regulation of key factors in different tissues against 20S degradation might be one major mechanism of protection and survival against endogenous and environmental stressors and requires investigation. The proposed studies will investigate the central hypothesis that NQO1 and NQO2 control key tissue factors/pathways that leads to protection against PBS and cigarette smoke-induced bladder cancer and lung emphysema. The studies will also determine the in-depth mechanism of NQO1 and NQO2 control of factors. Three aims are proposed. Aim 1 will determine if NQO1 mice demonstrate PBS and test the hypothesis that the loss of NQO1 alters key factors in control of mitochondrial biogenesis, energy metabolism, membrane integrity, and additional yet unidentified pathways that leads to PBS. In addition, investigate the susceptibility of NQO1 and NQO2 deficient mice to cigarette smoke-induced bladder cancer. Aim 2 will investigate in vivo role of NQO1 and NQO2 in cigarette smoke-induced lung emphysema. In addition, identify NQO1/NQO2 control of factors in protection against lung emphysema. Aim 3 will study in-depth mechanism by investigating the central hypothesis that NQO1 and NQO2 regulation of key factors against degradation by 20S proteasomes leads to protection against chemical carcinogenesis and PBS. The studies are clinically relevant since a significant number of individuals are deficient in NQO1 and NQO2, or both due to mutations/gene alterations.